Air-lift vehicle and filament skirt therefor



AIR-LIFT VEHICLE AND FILAMENT SKIRT THEREFOR Filed May 1, 1964 May 3, 1966 R. w. TIBBETTS 2 Sheets-Sheet 1 INVENTOR. jgvzrzaizd WJZZZBZZJ MM W AIR-LIFT VEHICLE AND FILAMENT SKIRT THEREFOR Filed May 1, 1964 May 3, 1966 R. w. TIBBETTS 2 Sheets-Sheet 2 V llllllIllllllllIlllI|IllllllhllllIllllllllhllllllllllllll I 'llllllllllllllllllllllllllllllllllllllllllllllllllllllllllll United States Patent 3,249,167 AIR-LIFT VEIHCLE AND FILAMENT SKIRT THEREFOR Raymond W. Tibbetts, Camden, Maine, assignor to Tibbetts Industries, Inc., Camden, Maine, a corporation of Maine Filed May 1, 1964, Ser. No. 364,247

2 Claims. (Cl. 180-7) This invention relates to the' skirt construction of a boat or other vehicle, and more particularly relates to an improvement over the structure shown in the copending application for Air-Lift Boat, Serial No. 59,560, nOW Patent No. 3,137,262, filed September 30, 1960, of which applicant is a co-inventor.

An object of the invention is to provide a skirt for a boat or other vehicle which has minimum friction with the underlying water or other medium, which is simple and economical in construction and which is durable and reliable in use.

In particular it is an object of this invention to provide a peripheral skirt for the hull of a boat or other ground effect machine, the skirt being in the form of a brush comprising a multiplicity of substantially vertical filaments or bristles associated closely together to 'provide a sufficient barrier for the air pressure under the hull of the vehicle, while being resilient enough to bend inward in response to the pressure exerted by waves, rocks or other obstacles while the vehicle is in forward motion.

For the purpose of illustration of a typical embodiment of the invention is shown in the accompanying drawings in which:

FIG. 1 is a plan view of a boat embodying the present invention;

FIG. 2 is a rear view of the boat;

FIG. 3 is a section on line 3.3 of FIG. 1;

FIG. 4 is a bottom view of two adjacent brush sections showing how they overlap, and showing the labyrinth arrangement of the filaments;

FIG. 5 is a section on line 5-5 of FIG. 1;

FIG. 6 is a bottom plan view of the boat;

FIG. 7 is a transverse detailed section showing a modification; and

FIG. 8 is a similar section showing another modification.

In the illustration the boat comprises a bottom 1 comprising closed-cell plastic foam, sides 2 and a rear end' 3. The forward end of the boat has an air inlet 4 and a fan 6 for pumping air in through the inlet. Except over the cockpit 7 the boat has a cover 8. Extending between the bottom 1 and the cover 8 is a transverse partition 9 and longitudinal partitions 11 to form enclosed air compartments, a transverse compartment 12 at the forward end of the boat and a longitudinal compartment 13 along each side of the boat. The bottom 1 has two longitudinal slots 17 and transverse slots 18 through which air may flow from the compartments 12 and 13. This construction is described and claimed in the aforesaid application Ser. No. 59,560.

' According to'this invention the air flowing through the slots 17 and 18 is confined as a cushion by a skirt or row of brushes depending from the bottom of the boat around its periphery, the brushes at each side of the boat being indicated at 21, the bristles at the forward end being shown at vane 22 and the bristle vane 23 at the rear end being pivotally mounted at 24 to swing about a transverse axis between a depending position and the elevated position shown in FIG. 5 in response to a control lever 26 and linkage 27,. thereby to control the air pressure under the boat at varying speeds. The aforesaid brushes may be continuous throughout the periphery except at the ends of pivoted vane 23, but prefvanes. FIG. 4 also shows the close-pack array of the fila-.

ments preventing direct paths for air by establishing a labyrinth of interstitial spaces between the filaments. The

filaments may be of hexagonal cross-section rather than circular, to provide an even closer grouping.

In the modification shown in FIG. 7 the filaments 31 of the brushes are hollow, the filaments are inclined inwardly, at least at their lower ends, or throughout their full length as shown, and the bottom of the boat has a slot 32 over each brush so that air can flow from the compartments 12 and 13 through the filaments thereby to help maintain the air cushion under the boat.

The modification shown in FIG. 8 is like that shown in FIG. 7 except in that the hollow filaments 33 are closed at the bottom, as indicated at 34, whereby the air pressure through slot 32 tends to stiffen the filaments. The brushes may comprise molded plastic and may be secured to the bottom of the boat by any appropriate means such as waterproof cement.

From the foregoing it will be understood that the aforesaid multifilament structure is resilient enough to bend due to the forward motion of the boat over obstacles, yet be returned to normal position by its own spring effect and by the internal air pressures of the compartment. It is not subject to catching and tearing on obstacles, as would be a continuous sheet. Such elasticity is provided by natural bristles, but due to the lengths involved and matters of durability, reliability and economy the filaments are preferably made of steel or of plastic, such as nylon. This will be of required flexibility while being weatherproof and water-impervious, and the filaments will stand much abuse when the vehicle is operated as a ground effect machine over dry land.

The filaments are of whatever length desired, depending upon the height of obstacles to be passed over without contacting the rigid portions of the vehicle. Each brush depends upon the internal pressures involved, which in turn are related to the weight and loading of the vehicle. Also, the brush will be stiffer at the fixed butt than at the free lower edge, further requiring thickness for proper stiffness at the lower edge. For higher objects or rougher seas long and thicker brushes with corresponding larger filaments may be utilized. If the vehicle is to be used only over water, the side brushes 21 may be of rigid construction as in the aforesaid application with only vanes 22 and 23 formed of filaments.

It should be understood that the present disclosure is for the purpose of illustration only and that this invention includes all modifications and equivalents which fall within the scope of the appended claims.

I claim:

1. For maintaining an air cushion under the bottom of a vehicle, a skirt comprising hollow resilient filaments,

3 4 the thickness of the skirt exceeding the diameter of the FOREIGN PATENTS filaments many times and the filaments being closely 1,319,034 1/1963 France packed to form a labyrinth of interstitial spaces between 1 339 687 the filaments, thereby to minimize the passage of air between the filaments, said hollow filaments being open 5 9/1963 France. 137,405 4/1961 U.S.S.R.

at their upper ends for communication with pressurized References cued by the Apphcant air. UNITED STATES PATENTS 2. A skirt according to claim '1 wherein said hollow 3 055 44 9/19 2 Vaughen' filaments are closed at their lower ends. 3 073 940 2 19 3 11 10 3,134,452 5/ 1964 Latimer-Needham. References Cited by the Examiner BENJAMIN HERSH P E UNITED STATES PATENTS "may xammer' 3,137,262 6/1964 'Tibbetts et a1. 1807 X 1 W 3,172,494 3/1965 CQckerell 1s0 7 15 SALES, Asslsfam Exammer- 

1. FOR MAINTAINING AN AIR CUSHION UNDER THE BOTTOM OF A VEHICLE, A SKIRT COMPRISING HOLLOW RESILIENT FILAMENTS, THE THICKNESS OF THE SKIRT EXCEEDING THE DIAMETER OF THE FILAMENTS MANY TIMES AND THE FILAMENTS BEING CLOSELY PACKED TO FORM A LABYRINTH OF INTERSTITIAL SPACES BETWEEN THE FILAMENTS, THEREBY TO MINIMIZE THE PASSAGE OF AIR BETWEEN THE FILAMENTS, SAID HOLLOW FILAMENTS BEING OPEN AT THEIR UPPER ENDS FOR COMMUNICATION WITH PRESSURIZED AIR. 